8S50ME-B9.5
The MAN 8S50ME-B9.5 is a low‑speed, 2‑stroke main propulsion engine delivering 29,840 kW at 127 rpm, featuring a camshaft‑driven exhaust valve and electronic fuel injection for improved efficiency and reduced part count.
Engine Specifications
Inspector Detail
✓ verified
▸
Designation decoded
8 stands for 8 cylinders, S for Super-Long-Stroke, 50 for 500 mm bore, ME-B for electronically controlled fuel injection with camshaft-controlled exhaust valve, 9.5 for Mark 9.5.
Background
The S50ME-B9.5 with 8 cylinders is one of the most widespread ME-B configurations. S/B 4.0 as a proven standard. Widely used in Supramax bulkers and MR tankers. 8 cylinders for maximum power with excellent vibration behavior.
Calculated metrics
Inspector checklist
- Cylinder liners: S/B 4.0 — significant side forces
- Piston rings: Butt clearance and height wear
- Alpha Lubricator: Dosing
- Crosshead bearing: Temperature across 8 cylinders
- Stuffing box: Drainage
- Piston rod: Deflection
- ME-B: Sensors, EICU
- Camshaft: Chain elongation
- Software
- Scavenge air box: Inspection openings
- Turbocharger: 1-2 TC
- Exhaust temperature across 8 cylinders
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust temperature by cylinder | 350–420 °C at MCR | Spread >15 °C → check injection |
| Scavenge air pressure | 2.3–3.0 bar | Drop → TC/cooler |
| Pmax | ±2 bar cylinder balance | Deviation → control system |
| Cylinder oil feed rate | 0.5–0.8 g/kWh | Calibrate Alpha Lubricator |
Common Failure Modes
Expert tips
- 💡 8×S50ME-B9.5 is one of the most widespread ME-B configurations — broad experience base, all service letters and best practices well documented
- 💡 8-cylinder S50 with S/B 4.0: Balanced configuration without particular challenges — standard ME-B maintenance applies
- 💡 ME-B with electronic injection: 3-5% fuel savings possible over MC — make sure the optimization is being used
Related components
Classification & regulatory
IMO Tier II. Tier III with EGR/SCR. EEDI. MARPOL Annex VI — VLSFO.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 23
Components & Design
Component data being added…
Technical Data
🤖 Ask about this model
One free question — answered like a marine engineer. No account needed.
Suppliers & Spare Parts
Direct links to manufacturer, datasheet, spare-parts portal and dealers — request access below.
📄 Request sourcing links & documentsCases, daily reports, timesheets and AI troubleshooting in the OceanSphere Marine app — free for 14 days.
Start free trial →Find manufacturers, repair shops and spare-part dealers in the Maritime Network — our global company directory.
Maritime Network →